Gritomatic Goniometer

[CasePeanut]

I just saw that Gritomatic has a new laser goniometer for what has to be the cheapest price ever for this type of device. Has anyone tried it?

 

[Old Biker]

I just saw that Gritomatic has a new laser goniometer for what has to be the cheapest price ever for this type of device. Has anyone tried it?

I just got one. It came today. It seems to work. It is easiest to read, when used on a full flat ground blade.

O.B.

 

[CasePeanut]

I just got one. It came today. It seems to work. It is easiest to read, when used on a full flat ground blade.

O.B.

Cool! Thanks for letting us know. About how long does it take it get a reading?

I imagine a microbevel would be pretty hard to see

 

[Old Biker]

What it is, is a laser pointer aimed directly at the zero mark in the center of the arc. When you hold a blade in the v notch directly in front of the pointer, it splits the beam and reflects it onto the graduations on either side of zero. With a flat ground blade you end up with two dots on each side of center. One from the primary flat grind and one from the secondary bevel. On say a hollow ground blade that primary grind mark is more of a line than a dot, because of the way the light reflects off of the curve of the grind. The secondary bevel mark isn't as distinct either, but it's usable.
Also there is no clamp to hold the blade in line with the laser. You have to do that by hand. You can tell when it's aligned correctly, when your hitting the same graduations on either side of center.

I would post some pictures, but would need four hands to take them, and I currently only have two hands, Maybe I can get someone to help me with that later.

O.B.

 

[CasePeanut]

What it is, is a laser pointer aimed directly at the zero mark in the center of the arc. When you hold a blade in the v notch directly in front of the pointer, it splits the beam and reflects it onto the graduations on either side of zero. With a flat ground blade you end up with two dots on each side of center. One from the primary flat grind and one from the secondary bevel. On say a hollow ground blade that primary grind mark is more of a line than a dot, because of the way the light reflects off of the curve of the grind. The secondary bevel mark isn't as distinct either, but it's usable.
Also there is no clamp to hold the blade in line with the laser. You have to do that by hand. You can tell when it's aligned correctly, when your hitting the same graduations on either side of center.

I would post some pictures, but would need four hands to take them, and I currently only have two hands, Maybe I can get someone to help me with that later.

O.B.

Thanks so much for the review! If I lived closer I would come over and help take pictures. It seems like a really useful tool. It would also show you when a knife has bevels that are way off.
They are out of stock now, but I am seriously considering one next time they are available

 

[Old Biker]

Ok here are a couple of pictures. The laser is way to bright for the camera and gets way overexposed, so a lot the detail you cans see with your eyes, is washed out. This first picture I was measuring the flat ground main blade of an old Colonial stockman. You can see the dots from the secondary bevel out at about 19°. I was also getting a primary grind of 3.5° to 4°. That is less clear in the picture.

In this picture, we used my Buck 110 with it's hollow ground blade. On this one I judge the secondary bevel to be 20°.

I hope this helps
O.B.

 

[CasePeanut]

Ok here are a couple of pictures. The laser is way to bright for the camera and gets way overexposed, so a lot the detail you cans see with your eyes, is washed out. This first picture I was measuring the flat ground main blade of an old Colonial stockman. You can see the dots from the secondary bevel out at about 19°. I was also getting a primary grind of 3.5° to 4°. That is less clear in the picture.

In this picture, we used my Buck 110 with it's hollow ground blade. On this one I judge the secondary bevel to be 20°.

I hope this helps
O.B.

Very helpful! Thank you for the pics. It seems like a really fast way to find the angles.

 

[Gritomatic]

O Old Biker , thank you so much for the review.

We will have a replenishment within 2 weeks. We will have two models, the reviewed one and "Pro" model with a knife fixed.

 

[Old Biker]

O Old Biker We will have two models, the reviewed one and "Pro" model with a knife fixed.

I think having a way to hold the blade will be really popular, with those buy this tool. Although the more I play with mine and get comfortable with using it, the less necessary I think a clamping feature is.

O.B.

 

[annr]

Thanks. Interesting.

 

[CasePeanut]

Gritomatic O Old Biker - Would the Goniometer work on the blades of a pair of scissors? that’s an edge where I think it would be very helpful

 

[Old Biker]

Gritomatic O Old Biker - Would the Goniometer work on the blades of a pair of scissors? that’s an edge where I think it would be very helpful

The goniometer has a 0° mark in the center, dead ahead of the laser, and then graduations going out to 40° on either side. Here is the problem with scissors. One side of the blade has no bevel. That is 0° on the goniometer. The other side has a very large angled bevel. So I checked a couple pairs of scissors I had handy with a protractor. The first, a pair of KAI kitchen shears, had a primary angle of 25° and a secondary bevel with a 75° angle. The second, were a pair of Tandy leather shears. They just have a single angle of 65°. So you are trying to measure a bevel of 65° to 75°. Or maybe even more? With a tool that goes to 40°. So I tried pivoting the blade, of the Tandy shears, to the side until the reflection hit the 40° mark. At that point the reflection from the flat side of the blade was at about the 30° mark. For a total of 70°.

Further checking show that the scissor blades have different bevel angles on each blade. Rechecking with the protractor gave me 45° on one blade and 70° on the other. On multiple checks with the goniometer I was able to match those numbers. I quit testing the KAI shears because, the narrow secondary bevel, made checking with the protractor iffy at best, and the yellow nonstick coating on the blades made for poor light reflection in the goniometer.

My protractor.

So in summery, it looks like you can make the goniometer work on scissors well enough, to get as accurate of a measurement, as you can get with the protractor shown above. Who well that measurement will translate into setting up, whatever tool you plan to use to sharpen the scissors with; I have no idea.

O.B.

 

[CasePeanut]

The goniometer has a 0° mark in the center, dead ahead of the laser, and then graduations going out to 40° on either side. Here is the problem with scissors. One side of the blade has no bevel. That is 0° on the goniometer. The other side has a very large angled bevel. So I checked a couple pairs of scissors I had handy with a protractor. The first, a pair of KAI kitchen shears, had a primary angle of 25° and a secondary bevel with a 75° angle. The second, were a pair of Tandy leather shears. They just have a single angle of 65°. So you are trying to measure a bevel of 65° to 75°. Or maybe even more? With a tool that goes to 40°. So I tried pivoting the blade, of the Tandy shears, to the side until the reflection hit the 40° mark. At that point the reflection from the flat side of the blade was at about the 30° mark. For a total of 70°.

Further checking show that the scissor blades have different bevel angles on each blade. Rechecking with the protractor gave me 45° on one blade and 70° on the other. On multiple checks with the goniometer I was able to match those numbers. I quit testing the KAI shears because, the narrow secondary bevel, made checking with the protractor iffy at best, and the yellow nonstick coating on the blades made for poor light reflection in the goniometer.

My protractor.

So in summery, it looks like you can make the goniometer work on scissors well enough, to get as accurate of a measurement, as you can get with the protractor shown above. Who well that measurement will translate into setting up, whatever tool you plan to use to sharpen the scissors with; I have no idea.

O.B.

Thank you O Old Biker for going the extra mile in trying that out!

it’s good to know about the limitations of the tool and also what’s possible with a good old protractor! I have a bunch of scissors to sharpen. Looks like I’ll stick to using a sharpie to check the angle.

 

[Gritomatic]

Scissors with one bevel can be measured. Place scissors on the spot shown on the picture as red and add 45 degrees to the value you read.

 

[pageyjim]

I just received the same model and it seems to work well by testing it against a few knives with known angles. Some blades seem a bit harder to tell because of their grinds I am sure but seems to be well made and easy to use.

 

[RustyIron]

The Pro model is sold out. Does anyone remember what the price was, or know what it will be? What's the difference between the Pro and the Lite Models?

 

[CasePeanut]

L

The Pro model is sold out. Does anyone remember what the price was, or know what it will be? What's the difference between the Pro and the Lite Models?

post from Gritomatic above says the Pro model has a clamp

 

[pageyjim]

From what I can tell the Lite which I have you have to hold the knife centered and push down and hold the laser button and then view. It looks like the Pro there is a magnet to line up the blade and an on and off switch for the laser. I also believe you can go a little wider with the angle reading with the Pro. The Lite seems awkward at first and to describe but isn't that bad.
I would still recommend using a sharpie but this gives you an immediate place to start. I think this can save you time and give you instant feedback and confidence in starting out. I can imagine veteran sharpeners saying this is not a necessary tool but I find it quite helpful.

 

[Glenn Goodlett]

Here is the pro version. Has a magnetic blade clamp. Adjustment for centering and an adjustment for zeroing. I paid $176.

I sharpened my Hinderer Full Track at 23 dps but the goniometer shows 23.5 dps. I can't really account for the difference but it is pretty darn close. Might be nice if it had a couple of standards and a adjustment to calibrate the thing and was made of metal. But, with that, it would cost a grand.

 

[pageyjim]

Check the blade at different locations and see what you get. Maybe the 1/2 degree difference is because you are near the heel of the knife.